Elements of the Host Protective Response (Part 1) Flashcards
1
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Immunology
A
- Study of the immune system and its response to invading pathogens
2
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Immune system
A
- The molecules, cells, tissues and organs that collectively function to provide immunity, or protection, against infectious pathogens
3
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Immunity
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- Resistance to disease, specifically infectious disease
4
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Immune response
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- A collective and coordinated response to the introduction of foreign substances in an individual
- Mediated by the cells and molecules of the immune system
5
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Initial defense mechanisms are barriers
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- Skin
- Acid and bile of the gastrointestinal tract
- Mucus at entry sites that inactivate and prevent entry of the foreign agents
6
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Innate immunity (nonspecific)
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- Mediates the initial protection against infections
- Relies on mechanisms that exist before infection
- Capable of rapid responses to microbes, and react in essentially the same way to repeat infections
7
Q
Adaptive immunity (specific)
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- Develops more slowly
- Mediated by lymphocytes and is stimulated by exposure to infectious agents
8
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Innate immune system
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- Also called natural or native immunity
- Always present in healthy individuals
- Prepared to block the entry of microbes and rapidly eliminate microbes that succeed in entering tissues
9
Q
Epithelial barriers
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- Prevent infections
10
Q
Soluble factors and stimulators (innate immune system)
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- Interferon
- Cytokines
- Chemokines
11
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Cellular component (innate immune system)
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- Eliminate microbes
- Natural killer cells, neutrophils & macrophages
12
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Cytokines
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- Hormone-like proteins that regulate immune responses
13
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Interferons
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- Proteins produced in response to viral and other infections
14
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Chemokines
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- Smaller proteins that are also regulatory for the immune system
15
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Adaptive immune system
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- Also called specific or acquired immunity
- Stimulated by microbes that invade tissues
- Adapts to the presence of microbial invaders
16
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Adaptive immunity is characterized by
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- Specificity for distinct macromolecules
- Memory (ability to respond more vigorously to repeated exposures to the same microbe)
17
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Stem cell
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- An undifferentiated cell that divides continuously
- Gives rise to additional stem cells and to cells of multiple lineages; “colony-forming unit
18
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Stem cells reside primarily in
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- Bone marrow
- Can also be isolated from the fetal blood in umbilical cords
- Rare in adult blood
19
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Differentiation of stem cells into functional blood cells is triggered by
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- Specific cell surface interactions with the stromal cells of the marrow
- Specific cytokines produced by these and other cells
20
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Differentiation of a common progenitor cell
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- The pluripotent stem cell
- Gives rise to all blood cells
21
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Pluripotent stem cell (progenitor cell)
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- Undifferentiated bone marrow cell that gives rise to the cells of the lymphoid, myeloid and erythrocytic lineages
22
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Cell differentiation
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- Acquirement of functions different from those of the original cell type
23
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Distinguishing types of white blood cells
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- Morphology & histologic staining
- Immunologic functions
- Intracellular & cell surface markers
24
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Cluster of differentation (CD)
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- Markers used to define white blood cell type
25
Class I major histocompatibility complex (MHC) antigens
- All nucleated cells express MHC I antigens
| - MCH I recognizes self from non-self
26
Primary lymphoid organs
- Generative lymphoid organs
- Sites of initial lymphocyte differentiation
- Essential to the development of the immune system
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Primary lymphoid organs (names)
- Bone marrow
| - Thymus
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Bone marrow
- Central cavity of bone is the site of generation of all circulating blood cells in the adult
- Site of B cell maturation
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Thymus
- A bilobed organ situated in the anterior mediastinum
| - Site of maturation of T lymphocytes from bone marrow-derived precursors
30
Secondary lymphoid organs
- Peripheral lymphoid organs
| - Places where dendritic cells and B and T lymphocytes reside and respond to antigenic challenges
31
Secondary lymphoid organs (names)
- Lymph nodes
- Spleen
- Mucosa-associated lymphoid tissue (MALT)
- Gut-associated lymphoid tissue (Peyer’s patches)
- Bronchus-associated lymphoid tissue (tonsils, appendix)
32
Swollen glands
- Proliferation of the lymphocytes in response to infectious challenge causes these tissues to swell
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Cells of the primary and secondary lymphoid organs express
- Cell surface adhesion molecules
| - Interact with homing receptors expressed on B and T cells
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Spleen and lymph nodes
- Encapsulated organs in which the macrophages and B and T cells reside in defined regions
- Promote development of adaptive immune responses
35
Spleen and lymph node location significance
- Facilitates interactions that promote immune responses to antigen
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Lymph nodes
- Site where immune response is initiated
- Located along lymphatic channels throughout the body
- Antigen capture and transport system
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Lymph
- Fluid from all epithelia and connective tissues is drained by lymphatics
- Transport the fluid (lymph) from the tissues to the lymph nodes
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Antigen presenting cells (APCs)
- Located in the lymph nodes
| - Sample the antigens of microbes that may enter through epithelia into tissues
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Swollen lymph nodes
- Denotes stimulation of immunity and cell growth
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3 layers of the lymph node
- Cortex
- Paracortex
- Medulla
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Lymph node cortex
- Outer layer
| - Contains mainly B cells, follicular dendritic cells & macrophages arranged in clusters (follicles)
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Lymph node paracortex
- Contains dendritic cells that bring antigens from the tissues to be presented to the T cells to initiate immune responses
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Lymph node medulla
- Contains B and T cells and antibody-producing plasma cells
44
Spleen
- Large abdominal organ that acts like a lymph node
| - Site of immune responses to antigens in blood
45
Spleen functions
- Filters antigens, encapsulated bacteria, and viruses from blood
- Removes aged blood cells and platelets
46
Spleen structure
- Consists of 2 types of tissue, the white pulp and the red pulp
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White pulp of the spleen
- Consists of arterioles surrounded by lymphoid cells (periarteriolar lymphoid sheath) in which the T cells surround the central arteriole
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B cells of the white pulp
- Organized into primary unstimulated or secondary stimulated follicles that have a germinal center
49
Germinal center of the white pulp contains
- Memory cells
- Macrophages
- Follicular dendritic cells
50
Red pulp of the spleen
- Storage site for blood cells
| - Site of turnover of aged platelets and erythrocytes
51
Cutaneous and mucosal associated lymphoid systems
- Under the epithelia of the skin
- Gastrointestinal and respiratory tracts
- Sites of immune responses to antigens that breach the epithelia
52
At any time, more than half of the body’s lymphocytes are in
- Mucosal tissues
| - Many of these are memory cells
53
Mucosa associated lymphoid tissue (MALT)
- Peyer's pathches
- Tonsils
- Lymphoepithelial organs
54
Tonsils
- Contain large number of mature and memory B cells
- Use their antibodies to sense specific pathogens
- Work with dendritic cells and T cells to initiate immune responses
55
Swelling of the tonsils
- May be caused by infection or a response to infection
56
Peyer's patches
- Special cells in the epithelium (M cells)
| - Deliver antigens to the lymphocytes contained in defined regions T [interfollicular] and B [germinal]
57
Lymphoepithelial organs
- Sample the microbes in the oral and nasal area
